Double sided PCB manufacturing process

2020-06-03 09:56Writer: qyadminReading:

Double sided pcb board

 
 Double sided PCBs (otherwise called Double Sided Plated Thru. or DSPT) circuits are the entryway to higher innovation applications. They take into account nearer (and additionally) directing. follows by substituting between a best and base layer utilizing vias. Today. double sided printed circuit board innovation. is the most mainstream kind of PCB in the business.
 

Double Sided PCBs circuits allow for closer (and more) routing traces by alternating. between a top and bottom layer using vias. Today, double sided printed circuit board technology. is the most popular type of PCB in the industry.


pcb manufacturing process Types


      The printed circuit board (PCB) acts as the linchpin for almost all today’s modern electronics. If the device needs to do some sort of computation. such as is the case even with simple items like a digital clock. chances are there’s a PCB inside of it. PCBs bring electronics to life by routing electrical signals. where they need to go to meet all the device’s electronic requirements. For this to happen, PCBs laid with a network of paths outlined in the traces. It’s these copper pathways that allow PCBs to direct electrical currents. around their surface.

     There are three main types of circuit boards that get manufactured on a consistent basis. and it’s important to understand the differences between each. so you can decide the right circuit board for your requirements. The three main types of circuit boards in current manufacture are:

 

     Single Sided pcb

Single side PCB. when made with a FR4 base have rigid laminate of woven glass epoxy material. which is then covered on one side with a copper coating that applied in varying thicknesses, depending on the application
 

      Double Sided pcb


Double sided boards. have the same woven glass epoxy base as single layer pcb. but, in the case of a double side pcb , there is copper coating on both sides of the board. also to varying thicknesses depending on the application
 

     Multi Layered PCB:


These use the same base material as single and double sided PCB board. but made with copper foil instead of copper coating the copper foil used to make “layers,” . alternating between base material. and copper foil until the number of desired layers reached.

      Now that you know a little bit about the basic types of PCB available. we’ll walk through the basic anatomy of a PCB to better familiarize you with it before moving on to how to build a PCB.
I will introduct the The manufacturing process double-sided PCB drilling

 

PCB board material


    what are PCBS made of,  Printed circuit boards, PCBs, can made from a variety of substances. The most used in a form of glass fibre based board known as FR4. This provides a reasonable degree of stability under temperature variation. and is does not breakdown , while not being expensive. Other cheaper materials are available for the PCBs in low cost commercial products. For high performance radio frequency designs. where the dielectric constant of the substrate is important. and low levels of loss needed. then PTFE based printed circuit boards can used. although they are far more difficult to work with.
 
        To make a PCB with tracks for the components, copper clad board is first obtained. This consists of the substrate material. FR4, with copper cladding on both sides. This copper cladding consists of a thin layer of copper sheet bonded to the board. This bonding is very good for FR4, but the very nature of PTFE makes this more difficult. and this adds difficulty to the processing of PTFE PCBs.
 

PCB material types

Substrate

The first, and most important, is the substrate, usually made of fiberglass. Fiberglass used because it provides a core strength to the PCB and helps resist breakage. Think of the substrate as the PCB’s “skeleton”.

Copper board for pcb

 Depending on the board type, this layer can either be copper foil or a full-on copper coated sheet. Regardless of which approach used, the funcation of the copper sheet for pcb is still the same. to carry electrical signals to and from the PCB. much like your nervous system carries signals between your brain and your muscles.

Solder Mask

 The third piece of the PCB is the solder mask, which is a layer of polymer that helps protect the copper
 so that it doesn’t short-circuit from coming into contact with the environment. In this way, the solder mask acts as the PCB’s “skin”.

Silkscreen

The final part of the circuit board is the silkscreen. The silkscreen is usually on the component side of the board used. to show part numbers, logos, symbols switch settings. component reference and test points. The silkscreen can also known as legend or nomenclature.
 

Manufacturing process of PCB

To begin with manufacturing pcb process. the pcb factory manufacturer &factory should create the plots first. Photoplots created based on the data supplied by the client. The required Gerber data is usually extracted from the customér's pcb style. (Eagle, Protel, Focus on etc.)

 

 
double layer PCB
 

 Cam-Bearbeitung
 

The info records from the many software solutions. backed in the PCB-P0OL standardized in thé Ext. Gerber File format (RS 274X).
The processed output document in Ext. Gerber Structure could supplied as preview.
 

Manufacturing PCB process 

 

PCB making Materials Preparation
 

      The copper-clad panels combined with the drill entry board. a backup bóard are after that cut to size.
The standard panel consists of a 1.6mm solid base materials, with a covering of 18µm copper on each side.
 

Drilling and pinning
 

      Now the reference & tooling hoIes drilled. Thé PCB-POOL paneI is after that pinned onto the CNC machine. 

pcb manufacturing process
 


Double sided PCB CNC Drilling

     By using CNC drill devices the through-hole pIated and component drills aré created. In this process, spindle speeds as high as 100,000 revolutions each minute recorded.
 

PCB plated Through hole process

     Right now an electrographic film (é.g. Palladium) is definitely electroplated to the wall structure of the drill cavity. this enables for galvanisation with copper that occurs at a later on stage. 
 


double PCB Brushing

      Because PCBs should be completley free from grease and dirt. they put through rigourous washing (e.g. by brushing). before proceeding to another stage.
 

Double sided circuit board Resist laminating

Under extreme temps and pressures the whole PCB-POOL panel . can laminated with a photosensitive dried out resist (LAMINAR 5038).
 

Double layer pcb Resist exposure

Using the before produced photoplots the resist subjected to UV light.
 

Double sided PCBS Resist development

Through cyclic building the uncovered panel created in a 1% sodium carbonate solution. The PCBs are actually ready for plating. 
 



Electroplated Conductor Configuration

      The tracks and páds which created, free of picture resist, are copper-pIated to a thickness óf approx. 35µm and fused with a 6µm -10µm tin film, safeguarding the tracks and pads through the final etching process.
 

Resist stripping


      The photoresist stripped aside with a 2.5% caustic potash answer. This lends itself tó the immersion and spráy coating processes.
 

Etching

The next thing is the spraying on óf a coating of ammonia remedy onto the copper film. eliminating any excess copper. as the galvanised tin shields the tracks and pads.
 

Tin stripping

Only after that will the tin. become removed utilizing a nitric acid centered tin-stripper. This Iends itself to thé dipping or spraying procedures.
 

Soldermask application

The soldermask could applied as a dried out film or an Iiquid lacquer in a hánging casting put into action. Following this comes the scréen-printing and spraying procedures.
 

Soldermask exposure




       Finally, using the before produced photoplots the soldermask is usually exposed to light. 
 

 Soldermask development

      The advancement of the uncovered PCB accomplished. through a cyclic structure in a 1% sodium solution. Thus all soldering factors and pads, which should be tin plated later on. cleared of soldermask.
 

pcb layers Silkscreen

      Utilizing a Direct Legend Printer. thé silkscreen is definitely immediately imprinted onto the soldermask. In this technique the printhead sprays thé screen-printing. described by Gerber data, straight onto the PCB.
 

Burning-in

      At a heat of 150°C the soldermask can tempered over an interval of approx. 60 moments.
 

layered PCB Surface finish

Chemical Nickel-Gold (ENIG)
       The pads produced by the solder paste covered with.  Chemical Nickel-Gold alongside the surface by way of vertical baths. The gold coating used to safeguard the nickel surface to make sure solderability. 

      in a word, With the bare PCB boards chosen and available the next step is to create the required tracks on the board. and remove the unwanted copper. The PCB manufacture  process  achieved using a chemical etching process. The most common form of etch used with PCBs is ferric chloride.
 
      To gain the correct pattern of tracks, a photographic process used. the copper on the bare printed circuit boards covered with a thin layer of photo-resist. It is then exposed to light through a photographic film. or photo-mask detailing the tracks required. In this way the image of the tracks passed onto the photo-resist. With this complete, the photo-resist placed in a developer. so that only those areas of the board where tracks needed covered in the resist.
    
      The next stage in the process is to place the printed circuit boards into the ferric chloride. to etch the areas where no track. or copper required. Knowing the concentration of the ferric chloride. and the thickness of the copper on the board. it placed into the etch froth e required amount of time. If the printed circuit boards placed in the etch for too long. then some definition lost. as the ferric chloride will tend to undercut the photo-resist.
 
      Although most PCB boards are manufacturing. using photographic processing, other methods are also available. One is to use a specialised accurate milling machine. The machine is then controlled to mill away the copper in those areas where the copper is not required. The control automated and driven from files generated by the PCB design software. This form of PCB manufacture is not suitable for large quantity. but it is an ideal option in many instances. where very small quantities of a PCB prototype quantities needed.
 
      Another method that is sometimes used for a PCB prototype is to print etch resistant inks. onto the PCB using a silk screening process.


.PCB MANUFACTURING PCB PROCESS

PCB drill  holes process :How is pcb made

 
      With the complexity of electronic circuits increasing.  it is not always possible to provide all the connectivity that required using the two sides of the PCB. This occurs quite when dense microprocessor and other similar boards are being designed. When this is the case multilayer boards required.
 
      The manufacture of multi-layer printed circuit boards. although it uses the same processes as for single layer boards. requires a greater degree of accuracy and pcb manufacturing process control.
 
      The pcb double sided  made by using much thinner individual boards, one for each layer. and these are then bonded together to produce the PCB. As the number of layers increases, so the individual boards. must become thinner to prevent the finished PCB. from becoming too thick. Additionally the registration between the layers. must be very accurate to ensure that any holes line up.
 
      To bond the different layers together the board heated to cure the bonding material. This can lead to some problems of warp. Large multi-layer boards can have a distinct warp on them if they are not designed . This can occur particularly if, for example one of the inner layers is a power plane or a ground plane. While this in itself is fine, if some significant areas have to left free of copper. This can set up strains within the PCB that can lead to warping.
 
 
      Holes. often called via holes. or vias needed within a PCB to connect the different layers together at different points. Holes may also needed to enable leaded components to mounted on the PCB. Additionally some fixing holes may needed.
 
      the inner surfaces of the holes have copper layer so that they connect the layers of the board. These "plated through holes" produced using a plating process. In this way the layers of the board can connected.
 
      Drilling is then accomplished using controlled drilling machines the data. supplied from the PCB CAD design software. It is worth noting that reducing the number of different sizes of holes. can help reduce the cost of the PCB manufacture.
 
      It may be necessary for some holes to only exist. within the centre of the board, for example when inner layers of the board. need to connected. These "blind vias" drilled in the relevant layers. before the PCB layers bonded together.
 
 
      When a PCB soldered it is necessary to keep the areas. that are not to soldered protected by a layer of what termed solder resist. The addition of this layer helps prevent unwanted short circuits. on the PCB boards caused by the solder. The solder resist  consists of a polymer layer. and protects the board from solder and other contaminants. The colour of the solder resist is deep green or red.
 
       to enable the components added to the board. either leaded or SMT to solder to the board , exposed areas of the board are "tinned" or plated with solder. boards, or areas of boards may be gold plated. This may be applicable if some copper fingers are to used for edge connections. As the gold will not tarnish, and it offers good conductivity it provides a good connection at a low cost.
 
      It is often necessary to print text and place other small printed idents onto a PCB. This can help in identifying the board. and also in marking component locations to aid in fault finding. A silk screen generated by the PCB design software used to add the markings to the board. after the other manufacturing processes for the bare board have completed.
 
 
      As part of any development process. it is advisable to make a prototype before committing to full production. The same is true of printed circuit boards where a PCB prototype manufactured. and tested before full production. a PCB prototype will need to manufactured as there is always pressure to. complete the hardware design phase of the product development. As the main purpose of the PCB prototype is to test the actual layout. it is often acceptable to use a different PCB manufacturing process. as only a small quantity of the PCB prototype boards will needed. But it is always wise to keep. as close as possible to the final PCB manufacturing process to ensure that few changes made. and few new elements introduced into the final printed circuit board.
 
 
      The PCB manufacturing processes is an essential element of the electronics production lifecycle. PCB manufacturing employs many new areas of technology. and this has enabled significant improvements to made both in the reduction of. sizes of components and tracks used. and in the reliability of the boards.

 The advantages instead of HAL are stress-free covering and the flat work surface 


 HEAT Levelling (HAL)

On the surface covering the pads. aré tin plated in á hot-air tin-pIating program. at a temp of around 270°C. In this process the PCB-P0OL panel immersed in liquid tin. which blown off with preheated air flow under a pressure óf approx. 5 Bars.
The technical specs sheet for the Iead-free tin. which utilized are available by clicking on the next link: Specifications.
 

Pinning

To avoid the panel from shifting during routing, it pinned down onto thé routing machine bed.
 

Routing

In the ultimate stages, the average person PCBs routed fróm the PCB-POOL paneI using a CNC Routing machine. This procedure entails spindle speeds of ovér 40,000 revs each minute and a feed price of 1m/min. 




 MULTI-LAYER Photoworks

     To begin with the plots created and Photoplots created based on the data supplied by the client. The required Gerber data is usually extracted from the customér's documents. (Eagle, Protel, Focus on etc.)
 

Resist laminating

      Under extreme temperature ranges and pressures the inner layers . Iaminated with a photosensitive dried out resist (LAMINAR 5038). 
 


 Resist exposure

Using the before produced photoplots the resist is definitely exposed to light.
 

Resist development

Through cyclic building the exposed. internal layers created in a 1% sodium carbonate solution.
 

Pressing

Only now are the specific layers pressed in á Multi-layer press át a max. heat of 175°C and a cyclic period of 90 mins for the layer framework.

 Another stage is drilling. The next manufacture process is valid for both muIti-layer and double-sidéd PCBs 
 

.

PCB drilling process Tips

 
       Printed Circuit Boards (PCBs) form the backbone of all major electronics. These miraculous inventions pop up in all computational electronics.  including simpler devices like digital clocks, calculators etc. For the uninitiated. a PCB routes electrical signals through electronic. which satisfies the device's electrical and mechanical circuit requirements. In short, PCBs tell the electricity where to go, bringing your electronics to life.
 
      PCBs direct current around their surface through a network of copper pathways. The complex system of copper routes determines the unique role of. each piece of printed circuit board.
 
       Before PCB design, circuit designers recommended to get a tour of a PC board shop. and communicate with fabricators face to face over their PCB manufacturing demands. It helps prevent designers making any unnecessary errors from. getting transmitted during the design stage. But. as more companies outsource their PCB manufacturing inquiries to overseas suppliers. this becomes unpractical. On this account. we present this article to provide a proper understanding of PCB manufacturing steps. it gives circuit designers and those new to. PCB Industry a clear view on how printed circuit boards manufactured. and avoid making those unnecessary errors.


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